In Roman times, the province of Aquitania originally comprised the region of Gaul between the Pyrenees Mountains and the Garonne River, but Augustus Caesar added to it the land between the Garonne and the Loire River. At this stage the province extended inland as far as the Cevennes and covered an area about one third of the size of modern France.

The 4th century AD saw the Roman province of Aquitaine divided into three separate provinces:

Aquitania prima, the north-eastern portion, including the territories which later became Berry, Bourbonnais, Auvergne, Velay, Gévaudan, Rouergue, Albigeois, Quercy and Marche

Aquitania secunda, the northwestern portion, with its capital at Burdigala (Bordeaux) and comprising the future Bordelais, Poitou, Saintonge, Angoumois and western Guienne